Interaction between nickel and copper in the rat

Two 42-d experiments were conducted with weanling male rats to study interactions between nickel and copper. In Experiment 1, a low-copper basal diet was supplemented with copper at 0 or 30 ppm and nickel at 0 or 30 ppm. Copper was added in Experiment 2 to a basal copper-deficient diet at a level of 0 or 15 ppm and nickel was supplemented at 0, 15, or 225 ppm. Responses to dietary nickel were dependent upon copper nutriture and experimental duration. Nickel had little effect on growth during the first 21 d of either study when added at low levels (15 or 30 ppm) to copper-deficient diets. Nickel supplementation depressed gains between 21 and 42 d in rats fed copper-deficient, but not copper-adequate, diets. Hematocrits and hemoglobin concentrations were not significantly affected by dietary nickel at 21 d. Nickel supplementation decreased hematocrits and hemoglobin values in copper deficient rats at 42 d in Experiment 1, but not in Experiment 2. Absorption of copper apparently was not reduced by nickel, since tissue copper concentrations were generally not decreased by increasing dietary nickel. Nickel supplementation increased lung and heart copper concentrations in Experiment 2. Liver iron was not affected by nickel, but spleen iron concentrations were reduced by nickel supplementation in copper-deficient rats in Experiment 2. The present studies suggest that nickel acts antagonistically to copper in certain biological processes.     

The effect of various dietary zinc concentrations on the biological interactions of zinc,copper, and iron in rats

Three groups (14 rats each) were fed one of the following diets for 8 wks: a control purified basal diet containing 12 ppm zinc, 5 ppm copper, and 35 ppm iron; the basal diet with less than 2 ppm zinc; or the basal diet supplemented with 1000 ppm zinc. Rats fed the zinc-deficient diet had decreased weight gain, moderate polydipsia, and intermittent mild diarrhea. The zinc-supplemented rats had a cyclical pattern of food intake and weight loss from weeks 5 to 8. Tissue concentrations suggest that zinc and copper were not mutually antagonistic with chronic dietary imbalances. If tissue element concentrations reflected intestinal uptake, then competition and/or inhibition of intestinal uptake occurred between zinc and iron. The fluctuations in tissue element concentrations that occurred with increased duration of the study were at variance with previous studies of shorter time periods. The dietary proportions of zinc, copper, and iron appear to influence zinc, copper, and iron metabolism at the intestinal and cellular transport levels over a given period of time.     

Dietary copper, simple sugars, and metabolic changes in pigs

Inadequate dietary copper is known to result in undesirable metabolic changes in rats and humans. Abnormal cardiac function, leading to sudden death, is a common finding when copper deficient rats are fed a 62% fructose diet. To further study the apparent mineral-carbohydrate relationship to cardiac physiology, 3 male and 3 female swine were randomly assigned to four groups (6 pigs per group) which were fed low copper (1.5 ppm) or copper supplemented (40 ppm) diets with 20% of calories from either fructose or glucose for 10 weeks. In agreement with results from other animal studies, copper deficient swine exhibited decreased plasma ceruloplasmin, erythrocyte superoxide dismutase and plasma lysyl oxidase activities and lowered serum copper. The copper deficient fructose group had the lowest aortic lysyl oxidase activity and hematocrit when compared to the other groups. The relative heart weight in the copper deficient fructose group was 93% greater than the other three dietary groups. The livers of copper deficient fructose fed pigs were also significantly larger. Two enzymes related to cardiac and hepatic function, aspartate and alanine aminotransferase were also measured. Copper deficiency significantly lowered alanine aminotransferase but there was no dietary effect on aspartate amino-transferase. The results of this project indicate that the pig is a sensitive model for the study of cardiovascular abnormalities which occur when fructose is consumed with a low copper diet.     

Interactions among nickel,copper, and iron in rats

In two fully crossed, three-way, two by three by three, factorially arranged experiments, female weanling rats were fed a basal diet supplemented with iron at 15 and 45 μg/g, nickel at 0, 5, and 50 μg/g and copper at 0, 0.5, and 5 μg/g (Expt. 1) or 0, 0.25, and 12 μg/g (Expt. 2). Expt. 1 was terminated at 11 weeks, and Expt. 2 at 8 weeks because, at those times, some rats fed no supplemental copper and the high level of nickel began to lose weight, or die from heart rupture. The experiments showed that nickel interacted with copper and this interaction was influenced by dietary iron. If copper deficiency was neither very severe or mild, copper deficiency signs of elevated levels of total lipids and lipid phosphorus in liver and plasma, and cholesterol in plasma, were made more severe by supplemental dietary nickel. Rats in which nickel supplementation exacerbated copper deficiency did not exhibit a depressed level of copper in liver and plasma. Also, although iron deprivation enhanced the interaction between nickel and copper, iron deprivation did not significantly depress the level of copper in liver and plasma. The findings confirmed that, in rats, a complex relationship exists between nickel, copper, and iron, thus indicating that both the iron and copper status of experimental animals must be controlled before data about nickel nutriture and metabolism can be compared among studies.     

Effect of dietary copper and zinc levels on tissue copper,zinc, and iron in male rats

The interaction between dietary copper and zinc as determined by tissue concentrations of trace elements was investigated in male Sprague-Dawley rats. Animals were fed diets in a factorial design with two levels of copper (0.5, 5 μg/g) and five levels of zinc (1, 4.5, 10, 100, 1000 μg/g) for 42 d. In rats fed the low copper diet, as dietary zinc concentration increased, the level of copper decreased in brain, testis, spleen, heart, liver, and intestine. There was no significant effect of dietary copper on tissue zinc levels. In the zinc-deficient groups, the level of iron was higher in most tissues than in tissues from controls (5 μg Cu, 100 μg Zn/g diet). In the copper-deficient groups, iron concentration was higher than control values only in the liver. These data show that dietary zinc affected tissue copper levels primarily when dietary copper was deficient, that dietary copper had no effect on tissue zinc, and that both zinc deficiency and copper deficiency affected tissue iron levels.     

Interactions among nickel,copper, and iron in rats

In two fully-crossed, three-way, two-by-three-by-three, factorially arranged experiments, female weanling rats were fed a basal diet supplemented with iron at 15 and 45 μg/g, nickel at 0, 5, and 50 μg/g, and copper at either 0, 0.5, and 5 μ/g (Expt. 1) or 0, 0.25, and 12 μg/g (Expt. 2) A gram of basal diet contained in Expt. 1 approximately 16 ng of nickel, 2.3 μg of iron, and 0.47 μg of copper; and in Expt. 2, 20 ng of nickel, 1.3 μg of iron, and 0.39 μg of copper. Expt. 1 was terminated at 11 weeks, and Expt. 2 at 8 weeks because, at those times, some rats fed no supplemental copper and the high level of nickel began to lose weight, or die from heart rupture. The findings demonstrated that relationships are complex among nickel, copper, and iron. Nickel interacted with copper and this interaction was influenced by dietary iron. Signs of copper deficiency were more severe when nickel was supplemented to the diet provided that copper deprivation was neither very severe nor mild. Iron deprivation apparently enhanced the antagonism by exacerbating copper deficiency. Signs of copper deficiency that were made more severe by nickel supplementation were depressed weight gain (Expt. 2), hematocrit (Expt. 1), hemoglobin, and plasma alkaline phosphatase activity; and elevated ratios of heart wt/body wt, kidney wt/body wt, and liver wt/body wt. Because nickel and copper have similar physical and chemical properties, the interactions between those two elements were probably the result, of isomorphous replacement of copper by nickel at various functional sites that interfered with some biological processes.     

Effect of copper on antioxidant ability and nutrient metabolism in broiler chickens stimulated by lipopolysaccharides

The aim of the experiment was to investigate the interaction between Cu intake, inflammatory challenge and oxidative stress in broiler chickens. Furthermore, it was tested whether plasma ceruloplasmin (Cp) could be a sensible parameter for dietary Cu. One hundred forty-four day old chickens were raised on a basal control diet without added copper (Group Cu-6.5, basal Cu content 6.5 mg/kg diet) or a diet supplemented with Cu at 8 or 50 mg/kg (Groups Cu-14.5 and Cu-56.5, respectively) with four replicates of 12 animals for each treatment. Starting on day 21, chickens were injected intraperitoneally with lipopolysaccharides (LPS) once a day for 3 days. Before this challenge, Group Cu-14.5 had the lowest gain and the feed to gain ratio was the highest. After injection of LPS, however, chickens of Group Cu-14.5 had the best zoo-technical performance. For chickens of Group Cu-6.5, LPS injection resulted in elevated rectal temperature, and lower erythrocyte superoxide dismutase (CuZn-SOD) activity, compared with the other groups. LPS injection increased plasma uric acid in Group Cu-6.5 significantly, but was without influence in Group Cu-56.5. At all Cu-levels, LPS injection increased erythrocyte CuZn-SOD activity and decreased thiobarbituric acid reacting substances. No significant difference in plasma Cp was found in chickens fed different dietary Cu. LPS injection significantly increased plasma Cp in Group Cu-56.5. The results suggest that varying dietary Cu levels seem to modulate the parameters involved in immunological responses and oxidant stress and that plasma Cp is not a reliable parameter for dietary Cu.     

Increase of dietary vitamin C improves haemocyte respiratory burst response and growth of juvenile grass shrimp,Penaeus monodon,fed with high dietary copper

Effects of dietary vitamin C (l-ascorbyl-2-monophosphate-Mg, C2MP-Mg) on growth, tissue copper (Cu) accumulation, and haemocyte superoxide anion production of juvenile grass shrimp, Penaeus monodon, fed with either adequate or high (8 x adequate) dietary Cu were studied. Three experimental diets were used: basal diet supplemented with adequate levels of both C2MP-Mg (40 mg kg diet(-1)) and Cu (20mg kg diet(-1)) (NC-NCu); basal diet supplemented with adequate C2MP-Mg and high Cu (8 x adequate) (NC-HCu); and basal diet supplemented with high C2MP-Mg (5 x adequate) and high Cu (HC-HCu). These were each fed to triplicate groups of shrimp (mean initial weight: 0.29+/-0.01 g) for 8 weeks. Highest (P< 0.01) weight gain, feed efficiency (FE) and protein efficiency ratio (PER) were observed in shrimp fed NC-NCu diet, intermediate in shrimp fed HC-HCu diet, and lowest in shrimp fed NC-HCu diet. Cu concentrations in hepatopancreas, muscle and haemolymph were highest in shrimp fed NC-HCu diet, followed by shrimp fed HC-HCu diet, and lowest for shrimp fed NC-NCu diet. Survival, total haemocyte count (THC) and intracellular superoxide anion (O-2) production were higher in shrimp fed NC-NCu diet than shrimp fed NC-HCu diet, whereas hepatosomatic index (HSI) was higher in shrimp fed NC-HCu diet than shrimp fed NC-NCu diet. However, all these parameters were similar in shrimp fed NC-NCu diet and shrimp fed HC-HCu diet. These data suggest that increase of dietary vitamin C improved haemocyte respiratory burst response and growth and prevented tissue Cu accumulation in P. monodon fed with high dietary Cu.     

Dietary beta- and gamma-cyclodextrins stimulation of hepatic metallothionein gene expression in rats

This study investigated whether hepatic metallothionein gene expression is affected by dietary cyclodextrins. Young male Wistar rats were fed a basal diet or cyclodextrin-supplemented (50 g of cyclodextrin per kg diet) diets for 7 d. Copper content in the liver did not show any significant changes among rats fed the basal, beta- and gamma-cyclodextrin diets. There were no differences in liver or serum zinc among groups. Copper content in serum was markedly decreased in rats fed the gamma-cyclodextrin-supplemented diet. Liver metallothionein mRNA levels were significantly elevated in both beta- and gamma-cyclodextrins-fed rats, but not in alpha-cyclodextrin-fed rats. Thus, the increase in hepatic metallothionein mRNA levels might be due to this mechanism except for the contents of copper and zinc in the liver.     

Effects of dietary zinc and copper on free radical production in rat lung and liver

The effects of dietary copper and zinc on free radical production in lung and liver microsomes were studied in male weanling rats. The rats were fed for 6 weeks on one of seven diets, with different copper and zinc concentrations representing low, adequate, and high dietary levels of copper and low and adequate levels of zinc. Rats were put on diets arranged in a 3 X 2 factorial design with copper and zinc supplementations of 0, 15, and 500 mg/kg and 0.5 or 100 mg/kg, respectively. The low copper diet depressed copper levels in both the lungs and liver, although zinc levels were unchanged in rats on the low zinc diets. Endogenous carbon-centered lipid radical production in microsomes induced by NADPH was measured using spin-trapping techniques. The low zinc diets increased free radical production in lung microsomes but not in liver microsomes. No change in free radical production was observed in lung or liver microsomes obtained from rats on low copper diets. The data indicate that endogenous free radical production is increased in lung microsomes as a function of dietary zinc deficiency but is not influenced by copper status.     

Effects of moderate copper deficiency on carbon tetrachloride-induced hepatotoxicity in rats.

Extreme copper deficiency has been shown to enhance CCl4-induced injury in rats. CCl4 hepatotoxicity was studied in rats with copper deficiency moderated by limiting deficiency periods to 5 or 6 weeks, using minimally adequate dietary zinc and including a marginal copper diet. Also, housing some rats in groups of six, rather than individually, was found to moderate the effects of low copper intake. Weanling male rats were fed copper at either 6, 2, or 0.2 mg/kg diet (adequate, marginal, deficient). Copper-zinc superoxide dismutase activity levels for singly and group-housed marginal rats were 80% and 93%, respectively, of adequate values. Values for deficient rats were 35% (singles) and 47% (group). In singly housed rats, a CCl4 dose of 400 microliters/kg intraperitoneally increased serum sorbitol dehydrogenase activities, indicators of cell membrane hepatotoxicity, in inverse proportion to dietary copper. A lower dose (100 microliters/kg) also produced smaller sorbitol dehydrogenase increases in adequate rats compared with deficients, but produced lowest increases in the marginals. The latter pattern also occurred in group-housed rats given the higher CCl4 dose, but the difference for adequate and marginal rats was not significant. The higher CCl4 dose, in singly housed rats, decreased liver glucose-6-phosphatase activities independently of copper intake. These activities are inversely proportional to microsomal lipid damage. In conclusion, moderate copper deficiency enhanced CCl4 hepatotoxicity, but the effect depended on injury criteria, CCl4 dose, and actual copper status as assessed by copper-zinc superoxide dismutase activities.     

Relationship between dietary copper concentration and acetylcholine-induced vasodilation in the microcirculation of rats

Dietary copper deficiency has been shown to significantly reduce acetylcholine (Ach)-induced vascular smooth muscle relaxation. The current study was designed to examine the relative relationship between dietary copper and the vasodilator response to Ach in the microcirculation of the rat. Male weanling rats were fed a purified basal diet supplemented with 6.0, 3.0, 1.5 or 0.0 microg Cu/g diet for 4 weeks to provide an adequate, two marginal, and deficient intakes of dietary copper. Arteriole dilation in response to increasing concentrations of acetylcholine (10(-7) to 10(-4) M) was measured in the in vivo cremaster muscle microcirculation for each dietary group. Liver copper and both aortic and erythrocyte Cu,Zn-SOD activity were used as indices of systemic copper status. Dilation to the increasing concentrations of Ach was only different in the 0 microg Cu supplemented group compared to the copper-adequate control values. However, the combined results showed an exponential increase in 10(-5) M Ach-induced vasodilation as liver copper concentration increases from 0 microg Cu/g dry wt. This relationship suggests that dilation is attenuated at liver Cu concentrations below 5 microg/g dry wt. The results indicate that Ach-induced vasodilation is copper-dependent but that the pathway is not very sensitive to short-term marginal restriction of copper intake.     

Effect of dietary copper sulfate, Aureo SP250, or clinoptilolite on ureolytic bacteria found in the pig large intestine

The predominant ureolytic bacteria in the pig large intestine were determined while growing pigs were fed a basal diet or basal diet plus copper sulfate, Aureo SP250, or clinoptilolite. Fecal samples were collected from four pigs fed each diet at 3, 9, and 14 weeks and analyzed for total colony counts and percent ureolytic bacteria. Fecal urease activity, ammonia nitrogen, and identity of the ureolytic bacteria were determined at 14 weeks. Copper sulfate and Aureo SP250 reduced the number of ureolytic organisms, with a marked decrease occurring in the Streptococcus spp., which made up 74% of the ureolytic isolates from the pigs on the basal diet. Other ureolytic species detected at lower concentrations were Staphylococcus spp., Selenomonas ruminantium, Bacteroides multiacidus, and Eubacterium limosum. Copper sulfate also reduced fecal urease activity (P less than 0.10). Fecal ammonia concentrations were not different between pigs fed the various diets. These data suggest that the streptococci are the most numerous ureolytic species in the pig intestinal tract and are significantly reduced by copper sulfate and Aureo SP250; however, only copper sulfate reduced intestinal urease activity.     

Suboptimal levels of dietary copper vary immunoresponsiveness in rats

The effects of severe, moderate, and mild copper deficiencies on cellular and humoral immunity were studied. Fifty male Sprague-Dawley rats, 5 wk of age, were fed diets containing 0.5, 2.0, 3.5, or 5.0 micrograms Cu/g for either 4 or 8 wk. Ten of the rats were fed the control diet, but were pair-fed with the 0.5-micrograms/g treatment group. All rats were immunized once with sheep red blood cells. Mean plasma-copper concentration reflected the dietary levels of copper, and ceruloplasmin activity correlated highly to plasma copper. Rats consuming suboptimal levels of copper responded differently to the deficiencies, so copper status varied among those animals. After 8 wk, cell proliferation, when stimulated by phytohemagglutinin, was dependent on the copper status of the animal. Severely deficient rats had consistently lower lymphocyte stimulation indexes for phytohemagglutinin and concanavalin A, but specific antibody response was not reduced. Immunoglobulin G (IgG) concentrations were variable for all rats, and immunoglobulin M (IgM) concentrations were lower for the severely deficient rats. Suboptimal dietary copper may alter immune function in rats, depending on the ensuing effect on copper status.     

Changes in copper and zinc status and response to dietary copper deficiency in metallothionein-overexpressing transgenic mouse heart

Previous studies have shown that cardiac-specific overexpression of metallothionein (MT) inhibits progression of dietary copper restriction-induced cardiac hypertrophy. Because copper and zinc are critically involved in myocardial response to dietary copper restriction, the present study was undertaken to understand the effect of MT on the status of copper and zinc in the heart and the subsequent response to dietary copper restriction. Dams of cardiac-specific MT-transgenic (MT-TG) mouse pups and wild-type (WT) littermates were fed copper-adequate (CuA) or copper-deficient (CuD) diet starting on the fourth day post delivery, and the weanling mice were continued on the same diet until they were sacrificed. Zinc and copper concentrations were significantly elevated in MT-TG mouse heart, but the extent of zinc elevation was much more than that of copper. Dietary copper restriction significantly decreased copper concentrations to the same extent in both MT-TG and WT mouse hearts, and decreased zinc concentrations along with a decrease in MT concentrations in the MT-TG mouse heart. Copper deficiency-induced heart hypertrophy was significantly inhibited, but copper deficiency-induced suppression of serum ceruloplasmin or hepatic Cu,Zn-SOD activities was not inhibited in the MT-TG mice. These results suggest that elevation in zinc but not in copper in the heart may be involved in the MT inhibition of copper deficiency-induced cardiac hypertrophy.     

Effect of dietary copper sulfate, Aureo SP250, or clinoptilolite on ureolytic bacteria found in the pig large intestine.

The predominant ureolytic bacteria in the pig large intestine were determined while growing pigs were fed a basal diet or basal diet plus copper sulfate, Aureo SP250, or clinoptilolite. Fecal samples were collected from four pigs fed each diet at 3, 9, and 14 weeks and analyzed for total colony counts and percent ureolytic bacteria. Fecal urease activity, ammonia nitrogen, and identity of the ureolytic bacteria were determined at 14 weeks. Copper sulfate and Aureo SP250 reduced the number of ureolytic organisms, with a marked decrease occurring in the Streptococcus spp., which made up 74% of the ureolytic isolates from the pigs on the basal diet. Other ureolytic species detected at lower concentrations were Staphylococcus spp., Selenomonas ruminantium, Bacteroides multiacidus, and Eubacterium limosum. Copper sulfate also reduced fecal urease activity (P less than 0.10). Fecal ammonia concentrations were not different between pigs fed the various diets. These data suggest that the streptococci are the most numerous ureolytic species in the pig intestinal tract and are significantly reduced by copper sulfate and Aureo SP250; however, only copper sulfate reduced intestinal urease activity.     

Effect of dietary caffeine and zinc on the activity of antioxidant enzymes,zinc, and copper concentration of the heart and liver in fast-growing rats

The purpose of this study was to determine the relationship between concentrations of Zn and Cu and the activities of superoxide dismutase and glutathione peroxidase in the heart and liver of young rat pups whose dams were fed a diet supplemented with caffeine and/or Zn. Four groups of dams with their newborn pups were fed one of the following diets for 22 d: 20% protein basal diet; the basal diet supplemented with caffeine (2 mg/100 body wt); the basal diet supplemented with Zn (300 mg/kg diet); or the basal diet supplemented with caffeine plus Zn. The Cu levels in the livers of the pups were decreased by maternal intake of the caffeine and Zn diet. The maternal intake of the caffeine diet increased Mn-superoxide dismutase (MnSOD) activity and Cu, Zn-superoxide dismutase (CUZnSOD) in the heart of the pups. On the other hand, the activity of Cu,ZnSOD was significantly reduced in the liver of pups whose dams consumed a caffeine, Zn, or caffeine plus Zn diet. Cu, ZnSOD activity in the liver of the pups seems to be correlated with Cu levels in the tissue. Selenium-dependent glutathione peroxidase (GSH-Px) activities in the heart and liver showed no difference among the groups. The effect of dietary caffeine and/or Zn on the activity of antioxidant enzymes in the heart and liver were different in young rats. The activities of these enzymes in the heart were lower than in the liver of 22-d-old rats. Our experiments indicate that the heart has limited defenses against the toxic effects of peroxides when compared to the liver.     

Marginal copper deficiency and atherosclerosis

Copper is an essential trace element in the maintenance of the cardiovascular system. Copper-deficient diets can elicit, in animals, structural and functional changes that are comparable to those observed in coronary heart disease. In this study, the effect of dietary-induced copper deficiency on aortic lesion development was measured by quantitative image analysis in C57BL/6 mice that are susceptible to diet-induced aortic lesions. The diets administered were severely copper deficient (0.2 mg/kg diet), marginally deficient (0.6 mg/kg diet), or copper adequate (6.0 mg/kg diet). Similarly, increased aortic lesion areas and elevated serum cholesterol were demonstrated in both deficient groups, compared with the copper-adequate group. Evidence for graded differences in copper status among the dietary groups was shown by the dose-response increase in liver copper concentration, copper-zinc superoxide dismutase and cytochrome-c oxidase activities, together with serum caeruloplasmin oxidase with increasing intakes of dietary copper. Despite the difference in copper status between the copper marginal and severely deficient groups, similar lesions found in both groups of mice suggest a threshold effect of copper deficiency on lesion formation.     

Consequences of copper deficiency are not differentially influenced by carbohydrate source in young pigs fed a dired skim milk-based diet

Carbohydrates (CHO) such as fructose (FR) or sucrose, but not starch (ST), aggravate the consequences of dietary copper (Cu) deficiency in rats. To evaluate whether this Cu X CHO interaction is pertinent to human health, the pig was used as an animal model. In two studies, 66 weanling pigs were fed dried skim milk (DSM)-based diets for 10 wk with 20% of the total calories provided as either FR, glucose, or ST and containing either deficient (1.0-1.3 micrograms/g diet) or adequate (7.1 micrograms/g) levels of Cu. Plasma and tissue levels of Cu, the activities of plasma ceruloplasmin ferroxidase and erythrocyte Cu, Zn-superoxide dismutase, and hematocrits were lower (p less than 0.05) in animals fed Cu-deficient diets. The relative cardiac mass of all Cu-deficient groups was greater (p less than 0.05) than that of animals fed Cu-adequate diets. These effects were in general unaffected by type of CHO. For comparison, weaned male rats were also fed DSM-based containing diets ST or FR with adequate or deficient Cu for as long as 10 wk. Rats consuming the Cu-deficient diets were characterized by significantly lower hematocrits, decreased tissue Cu levels, and enlarged hearts, regardless of the CHO source. Together, these data demonstrate that DSM-based diets are not suitable for delineation of potential Cu X CHO interactions, and one or more components of DSM may exacerbate the consequences of dietary Cu deficiency.